London (AFP) - European champions Arsenal capitalised on two terrible defensive blunders by Lyon on Sunday to come from behind and win the first leg of their Women’s Champions League semi-final 2-1.

The French league leaders went ahead in the 18th minute at the Emirates Stadium when Jule Brand scored with the visitors’ only shot on target in the first half.

But the Gunners rallied afer the break and levelled courtesy of an own goal from Ingrid Engen after goalkeeper Christiane Endler failed to gather the ball.

They took the lead when Olivia Smith took advantage of another mix-up at the back late in the game.

The two sides met at the same stage of the competition last season, with Arsenal winning 5-3 on aggregate before going on to lift the trophy with victory over Barcelona in the final.

Lyon drew first blood on Sunday when Brand surged forward and cut inside before beating Arsenal goalkeeper Daphne van Domselaar with a confident finish.

The home side thought they had been offered a way back into the game when they were awarded a penalty five minutes into the second half but the decision was overturned after a VAR check.

However, Arsenal were level in the 58th minute when Mariona Caldentey’s low free-kick somehow made its way into the net.

Lyon’s Endler mishandled the ball as Arsenal forward Stina Blackstenius darted into the six-yard box and the unfortunate Engen touched it into her own goal.

Kadidiatou Diani rattled the crossbar as the French team threatened to re-take the lead but it was Arsenal who scored again.

Endler and Engen collided after a moment of miscommunication and Smith collected the loose ball to slot into an empty net in the 83rd minute.

Arsenal boss Renee Slegers warned her team still had work to do.

“It’s only half-time but if you look at the game, a lot of bits played out how we wanted it,” she told the BBC.

“There was a phase in the first half where we wanted more aggression in our press and I think we had some great solutions at half-time.”

Lyon forward Ada Hegerberg described the goals her team conceded as “brutal”.

“You know in sports you get punished, but we stick together,” she said. “We have to accept it but find ways to move on.

“It’s important to take a step back and keep perspective.”

The second leg takes place in Lyon next weekend.

Bayern and Barcelona drew 1-1 in the other semi-final on Saturday.